1 files changed, 21 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/css-layout-api/constraints/support/constraints-fixed-block-size-quirky-body-iframe.html b/testing/web-platform/tests/css/css-layout-api/constraints/support/constraints-fixed-block-size-quirky-body-iframe.html
new file mode 100644
index 0000000000..da770e6caf
--- /dev/null
+++ b/testing/web-platform/tests/css/css-layout-api/constraints/support/constraints-fixed-block-size-quirky-body-iframe.html
@@ -0,0 +1,21 @@
+<style>
+body {
+  margin: 0;
+  --expected-block-size: 200;
+}
+
+.child {
+  background: green;
+}
+
+@supports (display: layout(test)) {
+  body {
+    display: layout(test);
+  }
+}
+</style>
+
+<!-- In Quirks mode, we should stretch to 100% of the inital containing block. -->
+<body>
+<div class="child"></div>
+</body>